Ammo Brief: 7mm Winchester Short Magnum

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A quick look at 7mm Winchester Short Magnum, the modern, short-action equivalent of the 7mm Rem. Mag.

Introduced in 2001 and intended for ranks of riflemen preferring 7mm cartridges, the 7mm Winchester Short Magnum WSM is crafted from the instantly popular .300 WSM case, necked down to accept .284-inch-diameter bullets. Also, the 7mm WSM shoulder was lengthened by .038 inch to prevent any possibility of chambering in a .270 WSM rifle.

The 7mm Winchester Short Magnum is the modern short-action equivalent of the 7mm Remington Magnum, a cartridge that showed untold numbers of hunters just how effective a flat-shooting, highly efficient .284 cartridge could be for North American and large African plains game. SSK Industries also re-barrels the AR-10 self-loading rifle for 7mm WSM.

At one point, Winchester and Browning offered several chamberings of their rifles in this round, including the M70 Extreme Weather, Featherweight, and Coyote bolt actions. Browning offered the round in several X-Bolt rifles and also the BAR Safari Rifle and BLR Lightweight 81 Takedown. Mossberg also chambered the round in its 4×4 rifle.

General Comments

For efficient and consistent powder burning, the 7mm Winchester Short Magnum continues the short-fat cartridge case geometry Winchester first popularized in the .300 WSM, a benchrest-proven concept for nearly three decades. Omitting a belt on the case, the 7mm WSM headspaces on the shoulder, which should provide for tighter headspacing tolerances and bettered accuracy potential.

Shooters are cautioned never to fire the slightly shorter, physically similar 7mm Remington Short Action Ultra Magnum in .270 WSM- or 7mm WSM-chambered rifles, as the .270 bore is smaller and the headspace would be excessive, leading to possible injury or firearms damage. The WSM line still enjoys moderate appeal, especially the .270 and .300 offerings.  

Editor's Note: This article is an excerpt of Gun Digest's Cartridge's Of The World.

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